1. Field of the Invention
This invention relates to a pair of male and female connectors fitted together to make an electrical connection therebetween, and more particularly to a waterproof packing axially compressed by the male and female connectors to form a liquid-tight seal between the two connectors.
2. Related Art
There have heretofore been used various connectors for electrically connecting a plurality of wires together, and one such connector has a waterproof construction for preventing rain water or the like from intruding into metal terminals fitted together.
For example, as shown in FIG. 4, a tubular collar 20 is fitted on a female connector 10 for angular movement about an axis thereof. Internal threads 21 formed in the inner surface of the collar 20 are threadedly engaged with external threads 32 formed on a fitting portion 31 of a male connector 30 shown in FIG. 5, so that the female and male connectors are threadedly connected together. As a result, male terminals 34 provided on the male connector 30 are fitted respectively into female terminals (not shown) provided on the female connector 10.
An annular packing 90 of a generally U-shaped cross-section is fitted on a disk-shaped flange 11, formed integrally on the female connector 10, to surround an outer peripheral edge portion of the flange 11.
As shown in FIG. 6, the packing 90 of a generally U-shaped cross-section includes a portion 91 for intimate contact with a surface 33 of the male connector 30 facing the flange 11, an axial wall portion 92 disposed radially outwardly of the flange 11, and a retaining portion 93 for retaining the two portions 91 and 92 on the flange 11.
When the female and male connectors 10 and 30 are threadedly connected together through the collar 20, the portion 91 of the packing 90 for intimate contact with the surface 33 is axially compressed between the flange 11 and the surface 33 of the male connector 30, and is held in intimate contact with them. As a result, there is formed a liquid-tight seal which prevents rain water or the like from intruding into the metal terminals provided at central portions of the female and male connectors 10 and 30.
In the above waterproof packing 90, however, a thickness T of the compression portion 91 axially compressed between the flange 11 and the surface 33 of the male connector 30 is uniform. Therefore, when the female connector 10 is threadedly connected to the male connector 30, the compression portion 91 of the packing 90 is axially compressed between the female and male connectors 10 and 30 to bulge radially outwardly into contact with the internal threads 21 formed on the inner surface of the collar 20. Therefore, the collar 20 is rotated, with the waterproof packing 90 held in contact with the internal threads 21, which invites problems that the outer peripheral surface of the packing 90 is damaged and that the packing 90 is caught between the internal threads 21 and the external threads 32, and is damaged.
Further, when the waterproof packing 90 is held in contact with the internal threads 21, the compression portion 91 is deformed, which leads to a possibility that the seal between the female and male connectors 10 and 30 is incomplete.
It may be proposed to increase the outer diameter of the collar 20 in order that the waterproof packing 90 will not be brought into contact with the internal threads 21. In this case, however, the mounting space must be increased, and the size of the connectors is increased, thus inviting a problem that the manufacturing cost and the weight are increased.